rear view mirror operation

trying to figure out the electronic rear view mirror I have the simple model with compass and temp only, there is a yellow light on the left side that is on all the time, what does it mean? I cannot find it in the Humongus manual i got with the truck. andit has 2 switches you push but all they do is shut off the display ? well anyway I like the auto dim mirror..:)

The yellow light is the indicator that the auto-dim feature is on.

thanks BIM